1. Field of the Invention
The present invention is generally related to a semiconductor device. More specifically, the present invention is directed to a semiconductor device and a method for fabricating such a semiconductor device in which a passivation film is formed with employment of both a high-K dielectric substance and a ferroelectric substance.
2. Description of the Prior Art
Recently, in order to obtain high-K dielectric constants, or utilize spontaneous polarization, high-K dielectric substances and ferroelectric substances, which are made of metal oxides, are employed as capacitors for semiconductor memory devices.
These semiconductor devices with employment of the above-explained high-K dielectric substances and ferroelectric substances are required to be operable under stable conditions in any kinds of environments of usage. To this end, in particular, moisture contained in air must be kept out. As a consequence, a passivation film is formed on a surface of such a semiconductor device so as to avoid penetration of moisture. As this passivation film, a silicon nitride (Si3N4) film has been widely utilized. This silicon nitride film is formed by that while a P-CVD (Plasma assisted Chemical Vapor Deposition) method is employed, material gas containing SiH4 is decomposed. As a result, the semiconductor device is exposed in hydrogen atmosphere during the film forming process. Furthermore, since the silicon nitride film deposited by this P-CVD method contains high concentration of hydrogen, hydrogen contained in this film may be sometimes diffused after the silicon nitride film has been formed.
When high-K dielectric substances and ferroelectric substances are reduced by hydrogen, characteristics thereof may be considerably deteriorated. As a result, there is such a problem that the passivation films similar to the conventional semiconductor devices are problematic to form in such semiconductor devices using high-K dielectric substances and ferroelectric substances.
The present invention has been made to solve the above-described problems, and therefore, has an object to provide a semiconductor device, and a fabricating method thereof, capable of suppressing diffusion of hydrogen in and also capable of maintaining high performance even when a passivation film is formed in such a device.
As a result of enthusiastic research in order to solve the above-described problems, Inventors of the present invention could find out the solutions capable of solving the above-explained problems. That is:
 less than 1 greater than  A semiconductor device, according to an aspect of the present invention, is featured by such a semiconductor device comprising: a semiconductor substrate; a ferroelectric capacitor formed on the semiconductor substrate; a first interlayer film covering the ferroelectric capacitor; a passivation film formed on the first interlayer film; and a hydrogen diffusion preventing film formed between the passivation film and the first interlayer film.
 less than 2 greater than  Also, the present invention is featured by that in the semiconductor device recited in the item  less than 1 greater than , at least one other interlayer film is formed between the first interlayer film and the passivation film.
 less than 3 greater than  Also, the present invention is featured by that in the semiconductor device recited in the item  less than 1 greater than , or the item  less than 2 greater than , the hydrogen diffusion preventing film is made of a tantalum oxide under amorphous state, or under microcrystalline state.
 less than 4 greater than  Also, the present invention is featured by that in the semiconductor device recited in any one of the items  less than 1 greater than  to  less than 3 greater than , the hydrogen diffusion preventing film is patterned.
 less than 5 greater than  Also, the present invention is featured by that in the semiconductor device recited in any one of the items  less than 1 greater than  to  less than 4 greater than , the hydrogen diffusion preventing film is formed in a non-reducing atmosphere.
 less than 6 greater than  A method for fabricating the semiconductor device recited in the items  less than 1 greater than  to  less than 5 greater than  of the present invention, is featured by comprising at least a step for forming a hydrogen diffusion preventing film under a passivation film and also substantially adjacent to the passivation film.